Actually, natural selection does explain it all.

"Intelligent Design" is another way of saying, "God did it." And if that's true, that raises a serious question about whether or not God is really perfect (the assumption being that God IS perfect because, after all, He's God). As environmental conditions changed over the eons, there were dead ends with a number of species, species that died out because they couldn't adapt, or their adaptation to new circumstances didn't work.

If "designed," then not really all that "intelligent." More in the nature of experimentation to see if some adaptation works or not. And—POOF!!—there goes "omniscience!"

But be of good cheer. This does not necessarily imply that God does not exist. It could mean that God knew that evolution was the way to do it. He started the process, then let it work without having to mess with it.

Let me be clear:   I am not asserting here that God either does or does not exist, I am just showing that, considering the number of species that died out because they could not adapt to new environmental conditions, "Intelligent Design" isn't really all that Intelligent, and it has the further flaw of calling God's omniscience into question.

Have a care, lest you shoot yourself in the foot.

Don Firth